A photodiode array, having a plurality of photodiodes 12 (n-type channel regions 121), and a light entrance portion 13, formed of an opening that is used to make light to be detected by photodiodes 12 enter, are provided in a substrate 10 of a photodetector 1A having an n-type substrate 101 and a p-type epitaxial layer 102. Furthermore, a carrier capturing portion 60, for capturing carriers generated at a substrate portion near the light entrance portion 13 and removes the captured carriers to the exterior via an electrode 61, is arranged from a layer portion of the epitaxial layer 102 that is positioned between the photodiode array 11 and the light entrance portion 13. A photodetector of a simple arrangement, which, when applied to a spectrometer, enables the positioning precision of components of the spectrometer to be improved, and a spectrometer using this photodetector are thus realized.